Computer controlled private automatic branch exchange (PABX) telephone systems are coming into greater use in commercial organizations. These systems provide enhanced flexibility in telephone communications and can provide a reduction in the cost of operating a telephone system. The computerized PABX can also be connected to other specialized computer systems for providing a customer services, such as credit verification.
The use of a computer to operate the PABX enables the user to provide automatic call distribution to a selected group of lines, place incoming calls in a hold status to receive a recorded message when no internal lines are available and to collect statistics on the number of calls, response and utilization of the telephone system. However, systems of this type frequently are designed to operate with unique digitally controlled telephone sets which are not compatible with the conventional two-wire telephone format. User equipment, such as a credit verification computer, on the other hand is most often designed to operate with the conventional two-wire telephone format. Therefore, in order to utilize the optimum equipment and features available, there exists a need to provide an interface between such incompatible systems. In particular, there exists a need to interface a digitally controlled telephone network, which operates in conjunction with a computerized PABX, to a conventional two-wire voice response computer to take advantage of the many features available through using the computer PABX.